Plane figures or shapes have two measurements namely length and breadth. Hence, they are called twodimensional shapes whereas a solid object has three measurements namely length, breadth, height or depth. Hence, they are called threedimensional shapes. Also, a solid shape occupies some space. Twodimensional and threedimensional figures can also be briefly named as 2D and 3D figures, respectively. Some twodimensional figures are shown below.
Some threedimensional figures are shown below:
Threedimensional figures have different numbers of faces, edges and vertices. All the flat surfaces of the figure are called faces, these faces are 2D shapes. The line segment where the faces of threedimensional figures meet each other is called the edge of the shape. The corners or points where the edges of the figure meet each other are called vertices (if one such point is there, then it is called a vertex).
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Important Questions Class 8 Maths Chapter 10 Visualising Solid Shapes
Consider a cuboid, the faces, edges and vertices are shown below:
The number of faces = 6
Number of edges = 12
Number of vertices = 8
Threedimensional shapes are further classified into two types.
 Polyhedrons (or regular polyhedrons)
 Threedimensional figures with curved surfaces
Polyhedrons, Prism and Pyramid
Name  Shape  Properties 
Cube  Faces = 6
Edges = 12 Vertices =8 

Cuboid  Faces = 6
Edges = 12 Vertices =8 

Prism (Triangular prism)  Faces = 5
Edges = 9 Vertices = 6 

Pyramid (square based pyramid)  Faces = 5
Edges = 8 Vertices = 5 

Triangular pyramid  Faces = 4
Edges = 6 Vertices = 4 
Threedimensional figures with curved faces
Name  Shape  Properties 
Cylinder  Faces = 3
(curved faces = 1, places surfaces =2) Edges = 2 Vertices = 0 

Cone  Faces = 2
(curved face = 1, plane surface = 1) Edges = 2 Vertices = 1 

Sphere  Faces = 1 (curved surface)
Edges = 0 Vertices = 0 
Nets for building 3D shapes
A twodimensional shape that can be folded to form a threedimensional shape or a solid is referred to as a geometry net. When the surface of a threedimensional shape is laid out flat showing each face of the shape, the obtained pattern is called a net. A solid may have different nets. In simple words, net is an unfolded form of a 3D figure.
Shape  Solid  Net 
Cube  
Cuboid  
Triangular prism  
Square pyramid  
Triangular pyramid  
Cylinder  
Cone 
Different views of a solid shape
A threedimensional object or shape can look differently from different positions (or sides) so they can be drawn from different perspectives, this is called visualising a solid shape. For example, views of a hut and a solid with three cubes from different sides are given below.
Example 1:
As shown in the above, front view of a hut is the combination of a square with a conical top, side view and top view is the combination of two rectangular surfaces.
Example 2:
In the above figure, one side of a solid has two square surfaces which are vertically connected, front view gas three square surfaces in L shape and top view has two square surfaces which are horizontally connected.